The present invention is related to the liquid inlet of small, portable dredges having hand-operated flexible suction hoses.
The suction hoses of small, portable dredges are relatively small and can easily become clogged during use. Attempts to keep the suction hose clear have conventionally involved the use of various screens and filter arrangements. Such devices must be cleaned often and are not entirely effective in keeping the hose clear. Long, narrow stones or twigs can be drawn through the stationary openings in such screens and pass into the suction hose.
The above problem has been solved to a limited degree for large industrial dredges as exemplified by U.S. Pat. No. 2,242,520 to Grundborg. The Grundborg dredge is supported on a barge and makes use of a barge supported power source for producing suction through a rigid, pivoted intake pipe. The open end of the pipe is enclosed by an "egg beater" shaped rotating screen. The screen is fitted over the intake end of the pipe. The base is rotated by a complex drive line extending the length of the pipe to the main power source. The screen is comprised of a number of knives that converge outwardly from the pipe opening. The knives serve a twofold purpose. First, they are used to chop through material on the bottom surface and can dig through compacted material. Secondly, the knives are used as strainers. They are rigid for the digging function and therefore can bind against large stones having projections that will fit between adjacent knives.
The power requirements, drive line and digger configuration, of the Grundborg dredge cannot be adapted for use in smaller, portable dredges presently in wide use by independent prospectors.
The present invention eliminates suction hose clogging problems through the use of a hand held liquid inlet with powered fingers rotating across an open intake. The fingers diverge from a point ahead of the suction hose opening to free ends situated radially outward and adjacent the intake opening. The fingers are spiral shaped to engage and deflect oversize material from the intake, while allowing free passage of proper size material. The fingers are rotated by a hand-held drive unit mounted directly to the fingers. Rearward ends of the fingers are free (unlike those of the Grundborg device) and will not become clogged by passage of rearwardly moving material.